Poly Methyl Hydrogen Siloxane Research Articles

Evaluation of antifoaming behaviour of polysiloxane mixed with fluoroalkyl as antifoam in degraded amine solution

The removal of CO2 from natural gas by absorption in amine-based solvent is a vital process for oil and gas industries. However, this process frequently struggles to meet its market specifications due to the degradation of amine solution by contaminants in the absorption system which often leads to foam formation and cause issues such as reduction in process performance. The aim of this study is to evaluate the antifoaming performance of Polymethylhydrogensiloxane (PMHS) with Hexafluorobutyl Acrylate (HFBA) antifoam in the methyldiethanolamine (MDEA) and piperazine (PZ) solution degraded by glycine, heptanoic acid and bicine. The antifoaming performance of PMHS + HFBA antifoam in this study has been found to be superior compared to the PDMS antifoam. The highest antifoaming performance for PMHS + HFBA and PDMS antifoam is in the presence of heptanoic acid with the highest average foaming tendency reduction of 61.91 % and 42.39 % respectively. This is attributed to the higher spreading coefficient of PMHS + HFBA antifoam that enables it to rupture foam at a faster rate. This study will demonstrate the importance of the continuous improvement of the use antifoams in reducing foam formation for absorption systems.

Production of nanocomposite films based on low density polyethylene/surface activated nanoperlite for modified atmosphere packaging applications

The modified atmosphere packaging films based on polyethylene nanocomposites reinforced with perlite nanoparticles were prepared using a blow molding machine. The perlite particles were first reduced to nano dimensions using an abrasive mill, then the porosity of nanoperlite was increased to improve their efficiency in absorbing ethylene gas. For this purpose, 6 normal sodium hydroxide solution at 50°C temperature was used. Finally, perlite nanoparticles were modified by polymethyl hydrogen siloxane silane compound. In each of the stages of grinding and modifying the perlite surface, the necessary tests including dynamic light diffraction test, nitrogen absorption test and ethylene gas absorption test were performed using gas chromatography method. The results showed that the size of perlite particles was reduced to 500 nm by using an abrasive mill, and the surface modification process increased the specific surface area of perlite by 10 times. Based on this, the amount of ethylene gas absorption in perlite nanoparticles with modified surface increased up to 3 times compared to normal perlite. The results of the gas chromatography test showed that the nanocomposite film based on polyethylene reinforced with 6% by weight of modified perlite nanoparticles has several times the efficiency in absorbing ethylene gas compared to the potassium permanganate sachets The results of the mechanical properties tests of nanocomposite film in comparison with pure polyethylene film showed that nanocomposite film has higher properties than pure polyethylene. The results of shelf-life tests of green tomatoes packed in nanocomposite film based on polyethylene reinforced with modified nanoperlite showed that green tomatoes can be stored for two months using the prepared modified atmosphere packaging.

High-performance lightweight foam concrete enabled by compositing ultra-stable hydrophobic aqueous foam

The major limitations of lightweight foam concrete are inferior mechanical properties and durability. This study designs a novel high-modulus hydrophobic foam to produce high-strength and durable foam concrete. Poly (methyl hydrogen)siloxane (PMHS) was employed to construct a hydrophobic boundary of hydroxypropyl methylcellulose (HPMC) foam. The produced hydrophobic foam bubbles exhibit a high modulus, fine bubble size, and exceptional thermodynamic stability. A dense foam wall of 8 μm in thickness functions as a structure for chemical loadings of inorganic-organic particles onto the viscoelastic bubble film. This facilitates their interaction effect of adsorption and chemical bonding, contributing to the hydrophobic nature of the foam wall. The resulting hydrophobic foam concrete shows low water adsorption and high mechanical strength. The hydrophobic foam concrete demonstrates superior chemical resistance and anti-chloride diffusion compared with normal concrete. This study might provide a practical strategy for designing high-performance lightweight foam concrete with significant potential as structural elements.

Fast Solution Blow Spinning of Lotus-Leaf-Inspired SiO2 Nanofiber Sponge for High Efficiency Purification.

Massive production of SiO2 nanofibers with both high durability and exceptional performance remains a significant challenge. Herein, a novel approach was introduced to achieve the massive production of SiO2 nanofibers with lotus-leaf-inspired surfaces by combining solution blowing spinning (SBS) and the polymer-derived ceramics method. Based on the SBS technique, three types of precursor nanofiber products were fast spined with methyl silsesquioxane polymer and polymethyl hydrogen siloxane employed as Si sources. The flow rate of the SBS spined Si-based ceramic nanofibers was enhanced to 20 mL·h-1. Furthermore, through the integration of hydrophobic-oleophilic SiO2 nanoparticles into the precursor solution, SiO2 nanofibers with lotus-leaf nanoprotrusion surfaces were fabricated. Nanoparticle-decorated SiO2 fibers demonstrated excellent hydrophobicity (138.3°), compression resilience (∼60%), proficiency in organic pollutant adsorption, high-temperature resistance (∼1100 °C), and outstanding thermal insulation properties (thermal conductivity of 0.0165 W·(m·K)-1).

Exploring damping behavior of novel polymer-derived aluminum alloy foam

Aluminum foams have excellent high-temperature damping capabilities. However, the use of metallic hydrides to synthesize foams reduces cell ductility, due to brittle intermetallics. This study demonstrates the damping behavior of AA2024 alloy foam synthesized using Polymethyl Hydrogen Siloxane as a foaming agent. Damping capacity was studied as a function of temperature (25 to 300 °C), frequency (1 to 80 Hz) and stress amplitude (1.5 to 21.5 MPa) using Dynamic Mechanical Analyzer. For comparison, monolithic samples of AA2024 at various conditions were also tested. The damping capacity of foams was about three times higher than the monolithic samples under certain conditions. The increased damping was a consequence of dislocation activity resulting from mode conversion around the numerous microscopic pores in the aluminum foam.

3D superhydrophobic lightweight foam concrete designed via in-situ foaming and self-assembled silicone microfilms

The poor durability of lightweight foam concrete, stemming from its highly porous and hydrophilic nature, is a major limitation for its wider application. Designing a superhydrophobic structure would be an effective approach to improving the durability of foam concrete. In this study, a facile strategy was developed to produce 3D superhydrophobic foam concrete using Poly(methyl hydrogen)siloxane (PMHS) by means of in-situ foaming and low surface energy characteristic. Results show that PMHS could be hydrolyzed and released hydrogen gas by reacting with the hydration product of Ca(OH)2. The resulting self-foaming lightweight concrete exhibits controllable average pore sizes ranging from 229 to 430 μm, with a density between 610 and 1177 kg/m3. The hydrolyzed PMHS self-assembles on the foam films, and the micrometer pores are carried with gel-like silicone microfilms through PMHS liquid–solid phase transition after 90℃ steam curing. With the synergetic effect of the dense silicone films and the particular pore frame, the superhydrophobic foam concrete demonstrates good fundamental properties, including thermal insulation and sound absorption, mechanical robustness, chemical durability, and weathering resistance. This study provides a practical solution for developing superhydrophobic lightweight concrete, which substantially enhances the durability of porous cement-based materials.

Tuning of Morphology and Surface Properties of Porous Silicones by Chemical Modification

The behavior of materials against water is a key element in many practical applications. Silicones are hydrophobic by nature and can be chemically modified to become hydrophilic or highly hydrophobic, while combining intrinsic surface properties with morphological details may lead to superhydrophobic materials. Chemically modified porous silicones and their surface properties have rarely been investigated. Our aim in this study was to tune the surface properties of porous silicone materials by a combination of chemical modification and emulsion templating The porous silicones were obtained by two cross-linking reactions in toluene–water emulsion, in mild conditions: dehydrocoupling of poly(methylhydrogen)siloxane (PMHS) and dimethyl-methylhydrogensiloxane copolymers and UV-initiated thiol-ene addition on a poly(dimethyl-methylvinyl)siloxane, respectively. Apart from the pores generated by water droplets, in the first process, additional large pores appeared due to hydrogen evolution. Their size and number diminished along with the cross-linking degree; thus, the porosity was tuned by adjusting the composition of the reaction mixture. Chemical modifications were performed in situ to introduce more hydrophobic groups (hexane and trimethylsilane) or hydrophilic groups (thioethanol), modifications that were followed by FT-IR spectroscopy. The inner morphology and powder wetting behavior of the crushed samples were investigated by SEM, tensiometry analyses, and contact angle measurements. The materials showed morphological particularities and surface properties that spanned from hydrophilic to superhydrophobic with lotus or petal effects.

Click chemistry of PMHS for fabrication of robust, transparent and hydrophobic silicone resin coating on wood substrate at room temperature

Based on click chemistry of poly(methylhydrogen)siloxane (PMHS), an environment-friendly method was proposed for in-situ fabrication of robust, transparent, UV-resistant and hydrophobic silicone resin coating (SRC) at room temperature by simply brushing a mixture of PMHS, tetramethyltetravinyl cyclotetrasiloxane (V4), and Karstedt catalyst on wood surface. The mechanism for click chemistry of PMHS and the continuous curing characteristic of SRC was discussed based on the characterization of SRC by FTIR and XPS. The effects of the mass ratio of PMHS to V4 and curing time on the properties of SRC and the modified wood were investigated. Results showed that SRC with the mass ratio of PMHS to V4 of 5:1 possessed the best mechanical stability, and the mechanical stability increased with curing time and temperature. SRC improved significantly the hydrophobicity and water-repellency of wood by increasing the water contact angle from 27.2° to 123.1° and decreasing the water absorption rate from 103 % to 16 %. SRCs showed excellent transparency with an average transmittance of 92.3 % at 400–1100 nm. The UV resistance of SRC was 6 times higher than that of varnish coating. The click chemistry of PMHS will find great application in rapid fabrication of functional coatings on wood surface by using PMHS and any vinylated reagent or micro-/nano-particles.

Critical role of support crystal structures on highly selective hydrodeoxygenation of lignin-derived vanillin over Pd/ZrO2 catalysts

Hydrodeoxygenation (HDO) of bio-oils obtained by rapid pyrolysis of biomass into high value-added chemicals generally required harsh conditions. Herein, three kinds of mixed-phase ZrO2 supports (denoted as ZSX, X = 2–4) with different crystal structure proportions were prepared by one-pot hydrothermal synthesis method, and their performance on the properties of Pd/ZrO2 catalysts were investigated for vanillin HDO. Pd/ZS3 exhibited excellent efficiency in HDO of vanillin, a typical model compound of lignin, achieving approximately 100% yield of 2-methoxy-4-methylphenol (MMP) in presence of n-butanol as solvent and polymethyl hydrogen siloxane (PMHS) as hydrogen donor under mild conditions (35 °C, 1 h). It was due to catalytic synergy of exposed metal active sites, oxygen vacancies (Ov) and acid sites to occur electron transfer and enhance interaction between Pd and ZrO2. By tuning the crystal structure of ZrO2 support, the influence of Ov and acid sites of Pd/ZrO2 over vanillin HDO performance was investigated, Pd/ZS2 with abundant Ov and Pd/ZS4 with substantial acid sites promoted hydrogenation and hydrogenolysis, respectively, Pd/ZS3 possessed preferable conversion and selectivity as having the properties of both at once. Additionally, reaction pathway was also proposed in which vanillin was converted to MMP by combining intermediate of 4-hydroxy-methyl-2-methoxyphenol (HMP) with active hydrogen species while removing water. This developed catalysts with different crystalline highlighted an enormous promise for HDO of bio-oils into green fuel under mild conditions.

Core–shell encapsulation of PMHS@EPDM onto BF surface for strengthening and toughening of BF/HDPE composites

Bamboo flour/high-density polyethylene (BF/HDPE) composite was strengthened and toughened simultaneously by the surface encapsulation of BF with poly(methylhydrogen)siloxane (PMHS) and Ethylene Propylene Diene Monomer (EPDM). A elastic PMHS@EPDM shell was fabricated on BF surface by successively spraying PMHS/hexane and EPDM/hexane solutions onto BF, based on the dehydrogenation and addition reaction of PMHS with BF and EPDM. It was found that surface encapsulation of wood at high PMHS content would simultaneously increase the strength and toughness of BF@PMHS/HDPE composite. The tensile strength and impact strength were increased by 54.2% and 9.9%, respectively as PMHS content was 3.3%. Furthermore, an encapsulation of BF@PMHS with EPDM further increased the strength and toughness by 5.1% and 14.7%. Compared with the pristine BF/plastic composites (BPC), the tensile, flexural and impact strength of modified BPC increased by 62.1%, 28.0% and 26.1%. The changes in the microstructure of the interface between BF and HDPE as a function of encapsulation of PMHS and EPDM and the relationship between chemical structure, microstructure and mechanical properties were discussed in detail. This work gave a novel MAH-free method for strengthening and toughening BF/HDPE or wood flour/high-density polyethylene (WF/HDPE) composites.

Facile Fabrication of Fluorine-Free, Anti-Icing, and Multifunctional Superhydrophobic Surface on Wood Substrates.

Building superhydrophobic protective layers on the wood substrates is promising in terms of endowing them with multiple functions, including water-repellent, self-cleaning, anti-icing functions. In this study, multifunctional superhydrophobic wood was successfully fabricated by introducing SiO2 sol and superhydrophobic powder (PMHOS). The SiO2 sol was prepared using tetraethoxysilane as a precursor and ethanol was used as the dispersant. The PMHOS was synthesized using poly(methylhydrogen)siloxane (PMHS) and ethanol. As a result, the obtained superhydrophobic wood had a water contact angle (WCA) of 156° and a sliding angle (SA) of 6° at room temperature. The obtained superhydrophobic wood exhibited excellent repellency toward common liquid (milk, soy sauce, juice, and coffee). The superhydrophobic layer on the wood surface also exhibited good durability after a series of mechanical damages, including finger wiping, tape peeling, knife scratching, and sandpaper abrasion. In addition, the obtained superhydrophobic wood showed excellent anti-icing properties.

Study of bladder release agent formulas and methods to evaluate their efficiencies by using reciprocating tribometer

Bladder is one of the most important components in tire manufacturing process. In tire industry, methods to prolong bladder service-life and good bladder coatings for non-stick surface has been acquired. Bladder coated with good release agents can help reducing nonconforming products and increasing production efficiency. In this work, semi-permanent release agent formulas were studied. A new method to evaluate release agent efficiency by using a reciprocating tribometer were also carried out. Polydimethyl siloxane (PDMS) release agent formulas were developed with and without polymethyl hydrogen siloxane (PMHS). Effects of metal salt cure catalyst were also studied. In this work, method of release efficiency test was developed by using a reciprocating tribometer according to ASTM G133-05. It can be used to determine coefficient of friction of the coated surface and durability of the coatings. Coating durability test was also confirmed by repeating compression molding test to determine the number of release cycles. It was found that film durability was improved by adding the metal salt catalyst and PMHS. As the PMHS loading was increased, film endurance was improved to an optimum loading. Friction coefficient of the coatings could be related to the mold release ability and durability of the release agents. The technique can be used to estimate the service-life of the coated bladders. It can be used as a guideline for development of mold release agents in tire manufacturing industry.

Synthesis of ZnO/TiO2-Based Hydrophobic Antimicrobial Coatings for Steel and Their Roughness, Wetting, and Tribological Characterization

AbstractWe synthesized novel TiO2/ZnO-phosphate (TP/ZP) and polymethyl hydrogen siloxane (PMHS)-based two-layer hydrophobic coatings with potential antimicrobial properties tuned for application on steel substrates. The mathematical method of topological data analysis was applied to surface roughness data. Wetting characterizations showed stable hydrophobic behavior of the two-layer coated samples. Through tribological characterization, we compared the friction behavior of uncoated steel samples and steel samples coated with different coating materials. The coefficient of friction of uncoated base materials (ranging from 0.221 to 0.269) and the two-layer hydrophobic coatings (ranging from 0.234 to 0.273) indicated that the coatings confer hydrophobic properties to the substrates without a notable change in the friction behavior. We observed the correlations between the wetting and friction behaviors and the average roughness of the coated samples. Analysis of the micrographs of the scratched surfaces revealed preliminary information about the durability and abrasion resistance of the coatings.

A facile method for constructing a superhydrophobic zinc coating on a steel surface with anti-corrosion and drag-reduction properties

Superhydrophobic surfaces are expected to be an effective technology for protecting marine metals. However, most of the reported methods are difficult to apply on steel surfaces. Herein, this study proposes a facile method of constructing a composite coating consisting of a zinc coating and superhydrophobic surface on a steel surface. A geopolymer-based zinc coating was precoated on the steel surface, and sand particles were used to form a rough micro structure. Then, the inherent alkaline species existing in the pore solution of the geopolymer trigger the hydrolysis-polymerization reaction of poly(methylhydrogen)siloxane (PMHS). After thermal curing, a superhydrophobic interface with a hierarchical micro/nanostructure can be assembled in situ on the coating surface. The prepared mechanism of the coating was characterized by SEM/EDS, XRD, CLSM, XPS, and the superhydropohocity performances were tested by water contact angle, drag reduction measurement and electrochemical analysis. The results show that the designed steel coating displayed a 45% drag reduction rate, 98% superhydrophobic repairable ability and excellent corrosion protection.

High Adhesion Superhydrophobic Surface Constructed by PDMS-co-PMHS Coatings Embedded with SiO2 Particles

Superhydrophobic surfaces have attracted attention due to their hydrophobic, self-cleaning, anti-icing, and oil/water separation properties. The present study used a nonwoven fabric as a flexible substrate and constructed a high-adhesive superhydrophobic surface by coating the fabric with polydimethylsiloxane (PDMS)-co -polymethyl hydrogen siloxane (PMHS) polymers and embedding mesoporous SiO2 nanoparticles. The water contact angle (WCA) of the superhydrophobic surface was up to 165.2° at a PDMS to PMHS ratio of 4:1. The adhesion to deionized water was 99.7 μN. High hydrophobicity was maintained, even after sandpaper abrasions and flowing water impact. The surface was resistant to acid, alkali, brine, strong oxidation, and heavy metal solutions. The coating exhibited anti-icing and oil/water separation properties. This study provides a facile and effective method for constructing multifunctional superhydrophobic coatings on flexible substrates.

Effect of poly(methylhydrogen)siloxane modification on adjusting mechanical properties of bamboo flour‐reinforced HDPE composites

Poly(methylhydrogen)siloxane (PMHS) was applied for hydrophobic modification of bamboo flour (BF) at room temperature based on the dehydrogenation between hydroxyl groups of BF and –Si–H of PMHS, and the effect of PMHS modification on mechanical properties of BF/HDPE (high-density polyethylene) (BF/HDPE) composites was investigated. It was found that the hydrophobicity of BF were significantly improved by PMHS modification, and the mechanical properties of BF/HDPE composites could be adjusted effectively. PMHS with reactive hydrogen content of 1.5 % was the best candidate modifier for improving the strength of BF/HDPE, while PMHS with reactive hydrogen content of 0.2 % is more suitable to improve the toughness of BF/HDPE. More importantly, with optimal weight ratio of PMHS to BF, the strength and toughness of BF/HDPE could be improved simultaneously. After a systematic discussion on the results of FTIR, XPS, SEM and the chemical structure of PMHS, the relationship between microstructure and properties of BF/HDPE composites was built and then the mechanism for PMHS modification on BF/HDPE composites was proposed.

Environment-Friendly and Two-Component Method for Fabrication of Highly Hydrophobic Wood Using Poly(methylhydrogen)siloxane.

Practical application of wood remains a great challenge because of its highly hydrophilic property. In this work, highly hydrophobic wood was produced using an environment-friendly and two-component package method. Poly(methylhydrogen)siloxane (PMHS) and inhibitor played the key role in the hydrophobicity of wood and the assembly process. The two-component package mechanism was discussed in detail. As a result, the water contact angles of the modified wood surface for the radial and cross sections were 139.5° and 152.9°, respectively, which provided the resultant wood high hydrophobicity and dimensional stability. The two-component package method afforded the wood good anti-fouling property and UV-resistance. In addition, the two-component package method could also be applied in functionalization of filter paper for oil/water separation.

Dehydrogenation-driven assembly of transparent and durable superhydrophobic ORMOSIL coatings on cellulose-based substrates

A novel dehydrogenation-driven assembly method was proposed to fabricate durable superhydrophobic SiO2/PMHS ORMOSIL (organically modified silica) coatings on cellulose-based substrates. Poly(methylhydrogen)siloxane (PMHS) played the key role in the durability of ORMOSIL coatings and the assembly process. The dehydrogenation-driven assembly mechanism of ORMOSIL was discussed in detail. Results indicated that the chemical property and microstructure of ORMOSIL could be controlled easily by varying the weight ratio of SiO2 to PMHS. The lotus-like ORMOSIL coating could be realized as the weight ratio of SiO2 to PMHS was 1:1. The ORMOSIL coating on wood surface was of self-cleaning property, good transparency and durability (including water-repellency and dimensional stability, mechanical and chemical stability, and UV-resistance). In addition, the SiO2/PMHS ORMOSIL gave cotton good oil/water separation ability. Finally, the dehydrogenation-driven assembly method was simple and low-cost, and it can be applied to fabricate durable superhydrophobic coatings on any other hydroxyl-containing substrates besides the cellulose-based substrates.

Cholesteric fluorescent liquid crystal polysiloxanes with different liquid crystal side chain lengths—Synthesis and properties

With polymethylhydrogensiloxane (PMHS) as the main chain, two series side-chain cholesteric liquid crystal polymers (ChLCPs) with different liquid crystal side chain lengths were prepared by hydrosilylation reaction. Then two series of cholesteric fluorescent liquid crystal polymers (FL-ChLCPs) were obtained by etherification reaction. The obtained FL-ChLCPs have both excellent mesomorphic behavior, and great photoluminescent property. We confirmed their chemical structures by FT-IR, and 1H NMR spectroscopy, and found them with excellent thermal stability by TGA. We characterized their mesomorphic behavior and thermal performance by POM, DSC and XRD, and confirmed all the polymers belonged to cholesteric phase. FL-ChLCPs emitted different-intensity fluorescence under UV light, and we found some regularity by PL spectrum.

Highly Hydrophobic Cotton Fabrics Modified by Poly(methylhydrogen)siloxane and Fluorinated Olefin: Characterization and Applications.

Highly hydrophobic cotton fabrics were obtained with poly(methylhydrogen)siloxane (PMHS) and a further fluorinated olefin modification. The chemical structures and microstructures of PMHS-modified cotton fabrics were characterized, and application of the resultant cotton fabrics in stain resistance and oil–water separation was demonstrated. PMHS chains with very low surface energy were grafted onto cotton fabric by the dehydrogenation reaction between –Si–H of PMHS and –OH groups of cotton fabric at room temperature. The water contact angle of PMHS-modified cotton fabric was 141.7°, which provided the modified cotton fabric with good stain resistance to waterborne pollutants. The separation efficiency of diesel from water was higher than 92% for 20 repeatable separation cycles. A further improvement in stain resistance to oil was also demonstrated by a further addition reaction of 1H,1H,2H-perfluoro-1-decene with PMHS-modified cotton fabric.